The mouth constitutes one of the major sites of infection. Infection can lead to debilitating disease of oral tissue and a clear association has also been observed between infection of oral tissue and disease or condition in other anatomical compartments.
Chronic periodontitis is one example of a disease of oral tissue. This is an inflammatory disease of the supporting tissues of the teeth leading to resorption of alveolar bone and eventual tooth loss. The disease is a major public health problem in all societies and is estimated to affect up to 15% of the adult population with severe forms affecting 5-6%.
The development and progression of chronic periodontitis has been associated with specific Gram-negative bacteria in subgingival plaque. The presence of Porphyromonas gingivalis in subgingival plaque has been strongly associated with disease.
The persistence of P. gingivalis in subgingival plaque from periodontitis patients after treatment (scaling and root planing) has been reported to be significantly associated with progressive alveolar bone loss. Furthermore an increase in P. gingivalis cell numbers in subgingival plaque has been shown to correlate with disease severity as measured by attachment loss, periodontal pocket depth and bleeding on probing.
Oral infection with P. gingivalis has been shown to induce periodontal bone loss in mice, rats and non-human primates. In addition, there has been increasing linkage of periodontal disease, and of P. gingivalis infection, with cardiovascular diseases and certain cancers.
Many other microbial pathogens, including other bacteria, fungi, virus and protozoa have been associated with disease of oral tissue and some of these pathogens also cause disease in other anatomical compartments via infection of oral tissue. Examples of the former include T. denticola and T. forsythia. Group A Streptococcus infection is an aetiological agent of rheumatic fever and rheumatic heart disease.
One problem has been that it is not clear how to obtain a strong protective response to a given microbial pathogen in circumstances where mucosal tissue has been chronically inflamed, or where acute inflammation of mucosal tissue has arisen from surgical or other dental intervention.
Reference to any prior art in the specification is not, and should not be taken as, an acknowledgment or any form of suggestion that this prior art forms part of the common general knowledge in Australia or any other jurisdiction or that this prior art could reasonably be expected to be ascertained, understood and regarded as relevant by a person skilled in the art.